Although the meson loop contributions can interpret the widths of \(\Upsilon (5S) \rightarrow \Upsilon (nS) \pi ^+ \pi ^-\) , the dipion invariant mass spectrum and the helicity angle distributions can not be reproduced simultaneously [1]}, especially for \(\Upsilon (5S) \rightarrow \Upsilon (2S) \pi ^+ \pi ^-\)  process, which is named the \(\Upsilon (2S)\)  anomaly [1]}, [3]}. Besides the anomalous widths, another important phenomenon observed in \(\Upsilon (5S)\)  decay is the bottomonium-like states \(Z_b^{(\prime )}\)  [4]}, [5]}. The particular properties of \(Z_b^{(\prime )}\)  have inspired theorists great interests. Since \(Z_b^{(\prime )}\)  was observed in the \(\Upsilon (nS) \pi , \ (n=1,2,3)\)  and \(h_b(mP) \pi , \ (m=1,2)\)  invariant mass distributions, thus the isospins of these two states are one. The most possible quark components are \(q\bar{q} b\bar{b}\) , which indicates these two states could be good candidates of tetraquark states [6]}, [7]}, [8]}, [9]}. Moreover, \(Z_b\)  and \(Z_b^{\prime }\)  are very close to the thresholds of \(B^\ast \bar{B}\)  and \(B^\ast \bar{B}^\ast \) , respectively, then authors in Refs. [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}, [17]}, [18]}, [19]}, [20]}, [21]}, [22]}, [23]}, [24]}, [25]}, [26]}, [27]}, [28]}, [29]}, [30]}, [31]}, [32]}, [33]}, [34]}, [35]}, [36]} considered these two states as molecular states composed of \(B^\ast \bar{B}\)  and \(B^\ast \bar{B}^\ast \) , respectively. Besides these resonance scenarios, in Refs. [37]}, [38]}, [39]}, \(Z_b\)  and \(Z_b^\prime \)  were interpreted as some special mechanisms, such as initial single pion emission mechanism [37]}, [38]} and cusp effects [39]}.
